﻿<p><em>IfcRelVoidsElement</em> is an objectified relationship between a building element and one opening element that creates a void in the element. It is a one-to-one relationship. This relationship implies a Boolean operation of subtraction between the geometric bodies of the element and the opening.</p>

<p>As shown in Figure 2, the insertion of a void into a wall is represented by the relationship <em>IfcRelVoidsElement</em>. The opening is created within the wall by <em>IfcWall(StandardCase) o-- IfcRelVoidsElement --o IfcOpeningElement</em>.</p>

<table border="0" cellpadding="0" cellspacing="0" width="502" summary="example for voiding">
<tr><td><img src="../../../figures/ifcrelvoidselements-fig1.png" alt="relationships for voiding" width="501" height="271" border="0"></td></tr>
<tr><td><p class="figure">Figure 2 &mdash; Relationship for element voiding</p></td></tr>
</table>

<blockquote class="history">HISTORY&nbsp; New entity in IFC1.0</blockquote>